ice: Set minimum default Rx descriptor count to 512

Currently we set the default number of Rx descriptors per
queue to the system's page size divided by the number of bytes per
descriptor. For 4K page size systems this is resulting in 128 Rx
descriptors per queue. This is causing more dropped packets than desired
in the default configuration. Fix this by setting the minimum default
Rx descriptor count per queue to 512.

Signed-off-by: Brett Creeley <[email protected]>
Signed-off-by: Anirudh Venkataramanan <[email protected]>
Tested-by: Andrew Bowers <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>

Author: bcreeley13

drivers/net/ethernet/intel/ice/ice.h

@@ -46,13 +46,20 @@ extern const char ice_drv_ver[];
 #define ICE_REQ_DESC_MULTIPLE	32
 #define ICE_MIN_NUM_DESC	ICE_REQ_DESC_MULTIPLE
 #define ICE_MAX_NUM_DESC	8160
-/* set default number of Rx/Tx descriptors to the minimum between
- * ICE_MAX_NUM_DESC and the number of descriptors to fill up an entire page
+#define ICE_DFLT_MIN_RX_DESC	512
+/* if the default number of Rx descriptors between ICE_MAX_NUM_DESC and the
+ * number of descriptors to fill up an entire page is greater than or equal to
+ * ICE_DFLT_MIN_RX_DESC set it based on page size, otherwise set it to
+ * ICE_DFLT_MIN_RX_DESC
+ */
+#define ICE_DFLT_NUM_RX_DESC \
+	min_t(u16, ICE_MAX_NUM_DESC, \
+	      max_t(u16, ALIGN(PAGE_SIZE / sizeof(union ice_32byte_rx_desc), \
+			       ICE_REQ_DESC_MULTIPLE), \
+		    ICE_DFLT_MIN_RX_DESC))
+/* set default number of Tx descriptors to the minimum between ICE_MAX_NUM_DESC
+ * and the number of descriptors to fill up an entire page
  */
-#define ICE_DFLT_NUM_RX_DESC	min_t(u16, ICE_MAX_NUM_DESC, \
-				      ALIGN(PAGE_SIZE / \
-					    sizeof(union ice_32byte_rx_desc), \
-					    ICE_REQ_DESC_MULTIPLE))
 #define ICE_DFLT_NUM_TX_DESC	min_t(u16, ICE_MAX_NUM_DESC, \
 				      ALIGN(PAGE_SIZE / \
 					    sizeof(struct ice_tx_desc), \